DXO is one of those interesting types of tests that produces a number based on a whole set of things that most people don't understand and which weights the relative value of those things in ways that are somewhat arbitrary.

People looking for simple answers ("I want the lens with the highest number!") often look at such things and make gross assumptions about what they mean ("Brand X is astonishing and Brand Y sucks!") that are off the wall.

Until you can explain to people what those "scores" actually mean and how they were derived and then see/show the difference using normal photographs, you can pretty much safely ignore them. Oh, and once you do understand them that way... you'll likely choose to ignore them. ;-)

...because several of the tested lenses with a high score in sharpness were tested on a D800 or D800E camera which simply has the best sensor resolution-wise. Canon's camera sensors cannot compete with this sensor.

Plus scores depend on the sensor you put behind the lens. Nikon has the highest resolution sensor right now (D800E) and Canon's lenses can't make up for the difference in resolving power. If Canon had a camera with the D800E sensor than most Canon lenses would probably score almost identical to their Nikon counterparts

Albino_BlacMan wrote:
Plus scores depend on the sensor you put behind the lens. Nikon has the highest resolution sensor right now (D800E) and Canon's lenses can't make up for the difference in resolving power. If Canon had a camera with the D800E sensor than most Canon lenses would probably score almost identical to their Nikon counterparts

ratsnest74 wrote:
ok, well who is the better source for such ratings? I hear so many people on this Canon forum saying Canon has the better lenses and I believed this until a Nikon shooter pointed this site out to me.

1st off...Canon glass doesn't mount on Nikon bodies and vice versa (while retaining AF)
so most of these "comparisons" are moot.
Try Photozone/Lenstip and shooters whose work you respect, preferably ones that shoot what you do.

As others have said, DxO's results are for the total system. Once Canon releases a high-MP body many will be surprised at how many of Canon's lenses will test higher than their Nikon equivalents, esp. toward the corners.

ratsnest74 wrote:
ok, well who is the better source for such ratings? I hear so many people on this Canon forum saying Canon has the better lenses and I believed this until a Nikon shooter pointed this site out to me.

DxO results are have a double bias; firstly, DxO intentionally biases results based on pixel count (scores are adjusted upwards based on sensor resolution) and secondly, the higher resolution sensors of the D800/D800E are capable of recording more of what the lens is resolving in the first place.

The only fair comparison is to test all the lenses on the same body, which is obviously problematic.

To back up a bit, what is the point of the question? Are you a Nikon or a Canon shooter? Are there specific lenses that you want/need for one brand or there other?

To back up even further, once you have determined that you need a particular lens with functional characteristics X, Y, and Z, "lens test" results may (or may not!) be useful in parsing out very small differences between otherwise identical options. However... in most cases they are almost completely irrelevant.

Let's say that you want a lens to cover (to make up numbers) the 20-75mm range at f/3 on your Nikocantaxony camera. You look at the "lens test" results and find out that Pensoncanikon makes the "best" 20-75mm f/3 lens which scores 73 on the DeadOX scale. You don't know what that means, but it is The Biggest Number so it must be best.

What do you do?

1. Sell your Nikocantaxony gear and replace it with a Pensoncanikon system so that you can have a lens that scores 73 instead of 72.

2. Find some third-party adapter than lets you put the Pensoncanikon lens on your Nikocantaxony camera, even though you'll have to give up AF and automatic aperture control and can't use filters.

3. Continue to use your Nikocantoxony setup and buy its deficient 72-rated lens and go on a forum and complain about how Nikocantoxony is "falling behind" Pensoncanikon.

One other thing, did you notice scores of 28 for a whole page? The differences must be trivial. I also note they list wide open scores, good for people who do razor thin dof stuff, who else cares?

What about vignetting, CA, distortion?

I could not find the Zeiss Distagon 21 in the top listings, yet a year or two back this was the king of the hill for landscapers. If you had to replace all your lenses each time a new batch arrived, it would get pretty expensive. Many of the top lenses were video anyway.

After owning lots of gear and 'testing' lots of lenses I have come to the conclusion that most modern, high quality lenses are already more than sharp enough for what I need.

Maybe I'm in the minority...but I find stuff like lighting, focus accuracy and processing to be far more influential to the final appearance/sharpness of an image than the minor differences between one very sharp lens and another very sharp lens.

I read on their site, that all tests are done in low-light conditions, because that is the critical performance condition. From their website:

DxOMark Score is based on low-light conditions (150 lux and 1/60s exposure time). We chose these conditions because we believe low-light performance is very important in photography today, and because photographers need to know how well lenses perform at their widest aperture.